Analysis into the Impacts of Short Circuit Capacity and X/R Ratio on Voltage Stability in Wind Power Plants

Abstract

The voltage stability of a distribution network connected Wind Power Plant (WPP) is dictated by the Short Circuit Capacity (SCC), Short Circuit Ratio (SCR), and short circuit impedance angle ratio at a given Point of Common Coupling (X/RPCC). This paper presents a comprehensive analytical study into the interconnection of WPPs to distribution networks through detailed power-voltage (PV), reactive power-voltage (QV), and SCR-voltage analysis studies. Analysis studies have been carried out using Induction Generator (IG) and Doubly-Fed Induction Generator (DFIG) WPP models connected to IEEE standard distribution systems. The study has shown that for small X/RPCC ratios, DFIG-based WPPs suffer from Power Quality (PQ) concerns. In the case of IG-based WPPs, PQ requirements can hardly be satisfied when wind power penetration is high for both large and small X/RPCC values. Analytical models, developed using QV analysis, have shown that voltage variations in response changes in wind reactive power at large X/RPCC buses is approximately two times greater than those with a small X/RPCC ratio. This research will guide decisions on the selection of feasible networks and WPP interconnection buses where steady-state voltage stability requirements can be best satisfied.